I have my 3.5 yr boy on a 12.5. Best thing ever. I bought him a Yamaha PW50 a few months ago, but he as still to small. And the untouchable added benefit of riding when ever and wherever, the Oset is the clear choice.
My boy has been riding on a custom track I built for him in my backyard, small backyard, maybe about 25x50 ft. The quick response of the electric bikes gets it going fast and quick around the tight stuff. With just a couple months of backyard practicing, maybe 20min a day prob average every other day, I felt he was ready for the real motocross track. Well to make the long story short, he graduated to the big track at just 3yrs 8months, and can do lap after lap, in some cases beating and keeping up to the bigger kids on 50's 5-7 years of age.
The key here, SEAT TIME. Our focus is motocross. My next delima is what bike to get him on next to compete in the motocross world. His skills I feel are good enough to get him on a KTM50 by the time he is about 4-4.5yrs. Actually, its a height problem. These Osets have really opened up major possibilities.
After watching these videos I saw last night.... it hit me like a train.
race car
street bike
F1
Dragster
http://www.youtube.com/watch?v=2_ukLgsGEzs&feature=related
street
http://www.youtube.com/watch?NR=1&feature=endscreen&v=369h-SEBXd8
Build your own electric motocycle
Im just going to find a used maybe blown up KTM50, and make it electric. Have him practice the wheels off of it just like his oset,and have another gas one for the races incase they protest it. We can worry about the clutch much later, most of the kids up to about 7ish I think are still riding fully auto KTM's anyways.
Sorry for the off subject, but your post frogger made sparked me again on converting a gas motorcycle to electric.